1. Field of the Invention
This invention relates to printing. The invention further relates to minimizing an unnecessary contact between photosensitive drums and a transfer belt.
2. Discussion of the Background
A color printing apparatus having a plurality of photosensitive drums has formed thereon toner images of each color. The toner images of each color are transferred to a transfer belt, and subsequently transferred to a recording sheet from the transfer belt. The color printing apparatus having this type of structure is called a tandem type.
In the tandem type color printing apparatus, unnecessary contact between the photosensitive drums and the transfer belt can be avoided to reduce wear by detaching the transfer belt from the photosensitive drums based on a print mode. Typical printing devices of this type are disclosed, for instance, in Japanese Patent No. 3325071 and Japanese Open-Laid Patent H06-102776 and 2005-242170. In the color printing apparatus of this type, when the print mode changes from a black and white mode to a color mode and vice versa, time is needed to attach and detach the transfer belt and the photosensitive drum which causes a decline of productivity in printing.